Thrust Foil Bearing Top Foil Bend for Higher Load Capacity
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Solution Overview
Problem
Thrust foil bearings face a challenge in maintaining load capacity due to increased bending in the radial direction on the downstream end of the top foil, which is exacerbated by the pressure of the fluid lubricating film, leading to a widened interval between the top foil and the thrust collar, and hindered inclination deformation in the circumferential direction.
Innovation Solution
A thrust foil bearing design featuring a corrugated bump foil supported by a base plate, with a top foil that has a bent portion bent towards the base plate, allowing for increased rigidity against radial bending and flexibility in the circumferential direction, and a mountain-shaped or curved bent portion to manage pressure distribution effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the top foil is made thick, then bending in the radial direction is reduced, but inclination deformation in the circumferential direction is hindered
Solution Approach 1:
The top foil is designed with non-uniform thickness distribution, being thicker at the upstream end and thinner at the downstream end. This local quality variation allows the foil to have sufficient rigidity at the upstream end to resist radial bending from fluid pressure, while maintaining flexibility at the downstream end to accommodate inclination deformation and taper angle formation, thereby resolving the contradiction between strength and adaptability
Solution Approach 2:
The invention introduces a new dimension of thickness variation along the circumferential direction of the top foil. Instead of using uniform thickness, the foil's thickness changes in the circumferential dimension, creating anisotropic rigidity where the foil exhibits different mechanical properties at different locations, enabling simultaneous satisfaction of radial bending resistance and circumferential flexibility requirements
2Adaptability or versatility
If the top foil is made thin, then inclination deformation in the circumferential direction is improved, but bending in the radial direction increases
Solution Approach 1:
The top foil employs local quality variation with different thicknesses at different circumferential positions. The thinner region at the downstream end provides the necessary flexibility for inclination deformation and taper angle formation, while the thicker region at the upstream end maintains sufficient strength to resist radial bending from fluid pressure, thus resolving the contradiction between adaptability and strength
3Strength
If the interval between the top foil and the thrust collar is widened, then bending in the radial direction is reduced, but the load capacity of the bearing decreases
Solution Approach 1:
The top foil is pre-formed with a specific thickness distribution pattern during manufacturing, with thicker sections positioned at the upstream end and thinner sections at the downstream end. This preliminary structural configuration ensures that under operating conditions, the foil automatically develops the appropriate rigidity profile to resist radial bending while maintaining optimal clearance for load-bearing fluid pressure distribution, thereby resolving the contradiction between bending resistance and load capacity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively suppresses radial bending on the downstream end of the top foil, enhancing the load capacity and maintaining a strong fluid lubricating film, even under high loads, while also improving the cooling effect through efficient fluid flow and temperature management.
Implementation Method 1
air is introduced between the top foil pieces and the thrust collar by the rotation of the thrust collar. The air forms a wedge-shaped fluid lubricating film between the top foil pieces and the thrust collar, and a load capacity of the thrust foil bearing is exhibited
Implementation Method 2
The air forms a wedge-shaped fluid lubricating film between the top foil pieces and the thrust collar
Implementation Method 3
a bent portion which is bent toward the base plate is formed on the other side of the top foil in the circumferential direction... one side in a circumferential direction of the insertion hole is attached to the base plate, and the other side in the circumferential direction of the insertion hole is a free end
Data Source
AI summary
A thrust foil bearing of this disclosure includes: a base plate provided with an insertion hole through which a rotation shaft is inserted; a corrugated bump foil placed around the insertion hole and supported by the base plate; and a top foil which is supported by the bump foil, and in which one side in a circumferential direction of the insertion hole is attached to the base plate and the other side in the circumferential direction of the insertion hole is a free end, and in the thrust foil bearing, a bent portion which is bent toward the base plate is formed on the other side of the top foil in the circumferential direction.